1996 Disco - Fast Idle

New issue that has just today surfaced: when cold the idle speed has jumped up to just over 1100rpm.

By the time the engine has warmed up that has risen to about 1700rpm.

Is there anything simple that could suddenly cause it to idle at these much higher rpm's?

Thanks in advance.

Jack

Sticky throttle cable, or is it EDC?

Have a look at this ..

Throttle cable is returning fine and the throttle cable adjustment is backed right out.

Can't make out where that adjuster in that file is. Is that on a V8?

300tdi disco ... is yours auto or does it have EDC?

Jack Wood said:

New issue that has just today surfaced: when cold the idle speed has jumped up to just over 1100rpm.

By the time the engine has warmed up that has risen to about 1700rpm.

Is there anything simple that could suddenly cause it to idle at these much higher rpm's?

Thanks in advance.

Jack

Click to expand...

Sticky stepper (do a search!)

Possible air leak if the stepper turns out to be ok.

Where is the most common place for an air leak? I can completely block the ****box inlet and the engine still runs at full idle speed. Is this normal?

And sorry, but seached the V8 forum for stepper info and it didn't bring anything up. Where is the stepper?

If you do a search for:

Idle control
Stepper motor
Poor idle

you should get lots of threads.

Anyway, stepper is on the left hand side of the plenum, near the back corner, all you need to do is unplug it then unscrew it from the housing. If you have got a large air leak I would recommend that you take off and clean the plenum and ram housing. Make sure the throttle butterfly is set correctly and that everything in the plenum is properly clean; don't forget to spray carb cleaner in all the small air ways etc. This is not a difficult job and doesn't really take that long to be honest.

When you re-assemble it all make sure you set the base idle speed; make sure your ignition timing is spot on.

There is a good chance that the idle air bypass pipe has perished, it is a black rubber pipe that runs around the back of the plenum, you won't miss it I'm sure.

HTH

Thank you very much Kev. Plenty for me to be getting on with there. I'll let you know how I get on.
Jack

Jack Wood said:

Thank you very much Kev. Plenty for me to be getting on with there. I'll let you know how I get on.
Jack

Click to expand...

You might have got better and quicker info if you'd said it was a V8 straight away ..

Heheheh, my bad .. didn't even realise it's in the V8 section .. extremely sorry. I shall stand in the dunces corner forthwith ..